Cationic multiblock thermoplastic elastomers

Abstract

The synthesis and characterization of a series of novel (AB) n multiblock copolymers, typically thermoplastic elastomers, containing polyisobutylene as the soft phase and polyamides as the hard phase are described. First, carboxyl ditelechelic polyisobutylene prepolymers and isocyanate ditelechelic polyisobutylene prepolymers were synthesized, both of which were subsequently reacted under solution polycondensation conditions with dicarboxylic acids and diisocyanates. The melting points of the polyamide hard phases were in the 223°-284° C. range. The decomposition temperatures (296°-337° C.) in air and nitrogen of these thermoplastic elastomers were quite similar; in contrast, these properties of polytetrahydrofuran-based thermoplastic elastomers are noticeably lower in air. Melt processing of these novel polyisobutylene-based thermoplastic elastomers is possible.

What is claimed is: 
     
       1. A multiblock thermoplastic elastomer comprising: a polyisobutylene soft segment and a polyamide hard segment; wherein said polyisobutylene segment and said polyamide segment form a repeating unit diblock copolymer that repeats at least two times, and wherein said repeating unit diblock copolymer is selected from the group consisting of formulas (I) and (II) ##STR13## where R, R' and R" are independently selected from the group consisting of C 2-20  aliphatic, cycloaliphatic, aromatic, aralkyl, alkaryl moieties and halogenated derivatives thereof;   R 1  is an initiator moiety of formula ##STR14## where R 2  is selected from the group consisting of C 1-24  alkyls, cycloaliphatic alkyls, aryls having from 1 to 4 phenyl rings, the rings being non-condensed or condensed, and halogenated derivatives thereof;   R 3  is selected from the group consisting of hydrogen, methyl or phenyl;   R 4  can independently be the same or different from R 3  ; and,   i is an integer that is at least 2;   m is a number from 1 to 50;   n is a number from 2 to 20;   y is a number from 9 to 100; and   z is a number from 9 to 100.   
     
     
       2. The polymer product of claim 1 wherein the repeating unit is selected from the group consisting of formula (I) ##STR15## wherein R, R' and R" are independently selected from the group consisting of C 2-20  aliphatic, cycloaliphatic, aromatic, aralkyl, alkaryl moieties and halogenated derivatives thereof; R 1  is an initiator of formula ##STR16## wherein R 2  is selected from the group consisting of C 1-24  alkyls, cycloaliphatic alkyls, aryls having from 1 to 4 phenyl rings, the rings being noncondensed or condensed, and halogenated derivatives thereof;   R 3  is selected from the group consisting of hydrogen, methyl or phenyl;   R 4  can independently be the same or different from R 3  ; and   i is an integer which is at least 2;   m is a number from 1 to 50;   n is a number from 2 to 20;   y is a number from 9 to 100; and   z is a number from 9 to 100.   
     
     
       3. The product of claim 1 wherein R 1  is aryl or a substituted aryl ##STR17## wherein R 5-12  are independently hydrogen or alkyl groups having from C 1-5  ; and R 13-15  are independently hydrogen or alkyl groups having from C 1-5  carbons or cycloalkyl groups having from C 4-8 .   
     
     
       4. A process for the preparation for a multiblock polymer product which comprises a polyisobutylene segment chemically bonded to a polyamide segment wherein the polyisobutylene segment and the polyamide segment form a repeating unit diblock copolymer wherein the diblock copolymer repeats at least two times which comprises the steps of: (a) cationically polymerizing isobutylene using an initiator having at least two functional end-groups which are hydroxide or capable of being converted into hydroxides to form a ditelechelic polyisobutylene;   (b) reacting the end-groups of the ditelechelic polyisobutylene with a dicarboxylic acid to form a carboxyl-terminated ditelechelic polyisobutylene prepolymer;   (c) reacting the prepolymer with at least one dicarboxylic acid in the presence of at least one diisocyanate; and   (d) recovering the diblock copolymer.   
     
     
       5. The process of claim 4 which wherein the step of reacting the prepolymer with at least one dicarboxylic acid and at least one diisocyanate occurs in a solvent. 
     
     
       6. The process of claim 5 wherein the solvent is a mixed solvent. 
     
     
       7. The process of claim 6 wherein the mixed solvent has at least one polar solvent and at least one non-polar solvent. 
     
     
       8. A multi-block thermoplastic elastomer prepared by the process of claim 4. 
     
     
       9. A process for the preparation for a multiblock thermoplastic elastomer which comprises a polyisobutylene rubbery segment chemically bonded to a polyamide hard segment wherein the rubbery segment and the hard segment form a repeating unit block copolymer wherein the unit repeats at least two times which comprises the steps of: (a) cationically polymerizing isobutylene using an initiator having at least two functional end-groups which are hydroxide or capable of being converted into hydroxides to form a ditelechelic polyisobutylene;   (b) reacting the end-groups of the ditelechelic polyisobutylene with a diisocyanate to form a diisocyanate-terminated ditelechelic polyisobutylene prepolymer;   (c) reacting the prepolymer with at least one dicarboxylic acid in the presence of at least one diisocyanate; and   (d) recovering the diblock copolymer.   
     
     
       10. The process of claim 9 which wherein the step of reacting the prepolymer with at least one dicarboxylic acid and at least one diisocyanate occurs in a solvent. 
     
     
       11. The process of claim 10 wherein the solvent is a mixed solvent. 
     
     
       12. The process of claim 11 wherein the mixed solvent has at least one polar solvent and at least one non-polar solvent. 
     
     
       13. A multi-block thermoplastic elastomer prepared by the process of claim 9.